The present invention relates to methods for producing laser-induced color images inside three-dimensional photographic media by using pulsed laser radiation.
A number of techniques for creation of colored images inside of transparent substrates by using natural light radiation and for production of laser-induced images created by pulsed laser radiation are well known.
U.S. Pat. No. 2,326,012 to Dalton discloses methods of producing color inside glasses and more particularly methods of making a glass article which includes melting a glass batch containing a reducing agent and a compound of copper, forming the glass into an article, exposing at least a portion of the article to short wave radiations and thereafter heating it for a time and at a temperature sufficient to color the exposed portion red. Another object of this invention is the method of making a glass article, which comprises interposing between a source of short wave radiation and a reduced glass containing copper and tin, a body having regions, which are opaque to the radiations and regions, which are substantially transparent to the radiations, irradiating the glass through the body with the radiations and subsequently heat treating the glass to develop a ruby colored image therein.
U.S. Pat. No. 2,422,472 to Dalton discloses a method creating an article comprising a substantially colorless reduced glass containing an irradiated reduction product of CuO and having within its mass a predetermined, latent, photographic image capable of being developed as a permanent red coloration in a colorless glass body by uniformly hearing the entire glass body.
The Russian invention No. 321422 to Agadjanov et. al. discloses a method of manufacturing decorative products inside a transparent material by changing the material structure by laser radiation. As disclosed, by moving a material relative to a focused laser beam, it is possible to create a drawing inside the material.
U.S. Pat. No. 3,715,734 to Fajans discloses a three-dimensional memory storage unit, which is prepared by carbonizing selected spots in a block of polymethylmethacrylate by means of a steeply converging laser beam. The energy of the beam is applied in pulses of such duration and at such intensity that carbonization takes place only at the focal point of the beam.
U.S. Pat. No. 4,092,518 to Merard discloses a method for decorating transparent plastic articles. This technique is carried out by directing a pulsed laser beam into the body of an article by successively focusing the laser beam in different regions within the body of the article. The pulse energy and duration is selected based upon the desired extent of the resulting decorative pattern. The effect of the laser is a number of three dimensional xe2x80x9cmacro-destructionxe2x80x9d (fissures in the material of the article) appearing as fanned-out cracks. The pattern of the cracks produced in the article is controlled by changing the depth of the laser beam focus along the length of the article. Preferably, the article is in the form of a cylinder, and the cracks are shaped predominantly as saucer-like formations of different size arranged randomly around the focal point of the optical system guiding a laser beam. The device used to carry out this technique is preferably a multi-mode solid-state, free-running pulse laser used in conjunction with a convergent lens having a focal length from 100 to 200 mm.
GDR Pat. No. 237 972 A3 to Wiederhold et al. discloses an opaque image pattern imbedded within the inner volume of an otherwise transparent article, without surface damage, using a focused, guided laser with an intensity (power density) at the focal area that exceeds the damage threshold. For instance, to create internal marks in a material having a damage intensity threshold of 40 kW/mm2 which is achievable with an average peak power of 20 kW, a laser with a 2,5 time higher peak power (50 kW) is employed, implying conditions under which ionization is reached.
U.S. Pat. No. 4,467,172 to Ehrenwald et al. discoses the method and apparatus g for laser engraving diamonds with permanent identification markings. A shallow penetration depth and narrow line width is achieved by using a harmonic conversion device to produce an output frequency which is second harmonic of the fundamental laser frequency in combination with a lens system having a short focal length to provide a high density pinpoint spot of laser energy.
U.S. Pat. No. 4,744,647 to Meshel et al. describes semi-opaque cornel contact lens and method of formation. A selected pattern of disruptions in the lens material of a soft or hard corneal contact lens is provided which substantially disrupts the undistorted transmisability of an image to the lens to render it semi-opaque. Preferably, these disruptions are formed by a laser beam, which cause the disruptions. The pattern may be used for coding of lens prescription or the like.
The Japan invention No. 61-288928 to Shigeru Hirukawa disclose the laser beam processing device, which permits partial and satisfactory removal of a resist film on a prescribed substrate or the like by condensing laser light of a CW laser, scanning said light on an object and processing the object while monitoring the processing condition of the object.
U.S. Pat. No. 4,843,207 to Urbanek et al., discloses a method of creating controlled decorations on the surface of a hollow symmetrical transparent article. This technique is preferably carried out on glass. The glass is preconditioned with a coating on the outer surface of the glass being approximately 1.2 mm thick and made of a material having at least 75% absorption of laser radiation. The technique is also carried out using a laser having a wave of length of 0.5 to 2 microns acting upon the external coating through the wall of the cylindrical glass article. The laser beam moves so that it is focused on the surface of the cylinder, and moves about the axis of symmetry of the cylinder to irradiate the aforementioned surface coating. As a result, the irradiated portions of the surface coating go through a phase change and a pattern is formed.
U.S. Pat. No. 5,206,496 to Clement et al. discloses a method and apparatus for providing in a transparent material, such as glass or plastic, a mark which is visible to the naked eye or which may be xe2x80x9cseenxe2x80x9d by optical instruments operating at an appropriate wavelength. The Clement et al. Patent describes a method and apparatus for producing a subsurface marking which is produced in a body such as bottle, by directing into the body a high energy density beam and bringing the beam to focus at a location spaced from the surface, so as to cause localized ionization of the material. In the preferred embodiment the apparatus includes a laser as the high energy density beam source. The laser may be a Nd-YAG laser that emits a pulsed beam of laser radiation with a wavelength of 1064 nm. The pulsed beam is incident upon a first mirror that directs the beam through a beam expander and a beam combiner to a second mirror. A second source of laser radiation in the form of a low power He-Ne laser emits a secondary beam of visible laser radiation with a wavelength of 638 m. The secondary beam impinges upon the beam combiner where it is reflected toward the second reflecting surface coincident with the pulsed beam of laser radiation from the Nd-YAG laser. The combined coincident beams are reflected at the reflecting surface via reflecting two other surfaces to a pair of movable mirrors for controlling movement of the beam. The beam then passes through a lens assembly into the body to be marked.
The Japan invention No 02-183681 discloses the marking method for improving the manufacturing yield of a semiconductor device by making the inner part of a transparent base plate selectively opaque and making it as the laser beam irradiates the inner part of the transparent base plate so that the focus is taken on it.
The Japan invention No. 03-120252 to Koji Kuwabara, et al. discloses the marking device and marking method. A laser beam from a UV region laser is swept on a resist by using scanning mirrors, by which the marking is executed.
Soviet patent publication 1838163 to P. V. Agrynsky, et. al discloses a process for forming an image in a solid media by processing of the optically transparent solid material by a beam of radiation with changeable energy for creation of the image.
WIPO Patent Document No. 96/30219 to Lebedev discloses a technology for creating two- or three-dimensional images inside a polymer material using penetrating electromagnetic radiation. The technology can be used for marking and for producing decorative articles and souvenirs. Specifically, laser radiation is used as the penetrating radiation, and carbonizing polymers are used as the polymer material. By these means, it is possible to produce both black and half-tone images in the articles.
U.S. Pat. No. 5,268,862 to Rentzepis et al. discloses a method for creating three-dimensional optical memory by two UV laser light beams, typically of 532 nm. and 1064 nm. Wavelength, to change from a first, spiropyran, to a second, merocyanine, stable molecular isomeric form by process of two-photon absorption.
U.S. Pat. No. 5,575,936 to Goldfarb discloses a process and apparatus where a focused laser beam causes local destruction within a solid article, without effecting the surface thereof The apparatus for etching an image within a solid article includes a laser focused to a focal point within the article. The position of the article with respect to the focal point is varied. Control means, coupled to the laser, and positioning means are provided for firing the laser so that a local disruption occurs within the article to form the image within the article.
U.S. Pat. No. 5,637,244 to Erokhin discloses a technique which depends on a particular optical system including a diffraction limited Q-switched laser (preferably a solid-state single-mode TEM00) aimed into a defocusing lens having a variable focal length to control the light impinging on a subsequent focusing lens that refocuses the laser beam onto the transparent article being etched. The laser power level, operation of the defocusing lens, and the movement of the transparent article being etched are all controlled by a computer. The computer operates to reproduce a pre-programmed three-dimensional image inside the transparent article being etched. In the computer memory, the image is presented as arrays of picture elements on various parallel planes. The optical system is controlled to reproduce the stored arrays of picture elements inside the transparent material. A method for forming a predetermined half-tone image is disclosed. Accordance to the method, microdestructions of a first size are created to form a first portion of the image and microdestruction of a second size different from the first size are created to form a second portion of the image. Different sizes of microdestructions are created by changing the laser beam focusing sharpness and the radiation power thereof before each shot.
U.S. Pat. No. 5,653,900 to Clement, et al. discloses a method and an apparatus for making a moving body of material. In a preferred embodiment, the apparatus includes at least one movable galvanometer mirror capable of moving the laser beam to create a mark of a predetermined shape.
U.S. Pat. No. 5,656,186 to Mourou, et al. discloses a method for controlling configuration of laser induced breakdown and ablation. The method comprises generating a beam of laser pulses in which each pulse has a pulse width equal to or less than the predetermined laser pulse width value. The beam is focused to a point at or beneath the surface of a material where laser induced breakdown is desired. The technique can produce features smaller than the spot size and Rayleigh range due to enhanced damage threshold accuracy in the short pulse regime.
U.S. Pat. No. 5,786,560 to Tatah et al. discloses a method of treating a material by generating an ultraviolet wavelength laser beam having femtosecond pulses; splitting the laser beam into a plurality of separate laser beams; directing these laser beams onto a target point within a sample such that the beams overlap to create an intensity sufficient to treat the sample.
U.S. Pat. No. 5,886,318 to A. Vasiliev and B. Goldfarb discloses a method for laser-assisted image formation in transparent specimens, which consists in establishing a laser beam having different angular divergence values in two mutually square planes. An angle between the plane with a maximum laser beam angular divergence and the surface of the image portion being formed is changed to suit the required contrast of an image.
EPO Patent Document 0743128 to Balickas et al. disclose a method of marking products made of transparent materials which involves concentration of a laser beam in the material which does not absorb the beam, at a predetermined location, destruction of the material by laser pulses and formation of the marking symbol by displacement of the laser beam. Destruction of the material at that location takes place in two stages. In the first stage, the resistance of the material to laser radiation is altered, while, in the second stage, destruction of the material takes place at that location.
Russian patent publication RU 20082288 to S. V. Oshemkov discloses a process for laser forming of images in solid media by the way of focusing of laser radiation in a point inside a sample which differs by following: with the aim to save the surface and the volume of the sample before the definite point and creation of three dimensional images, the sample is illuminated with the power density higher than the threshold of volume breakdown and moving the sample relatively to the laser beam in three orthogonal directions.
U.S. Pat. No. 6,087,617 to Troitski et al. discloses a computer graphic system for producing an image inside optically transparent material. An image reproducible inside optically transparent material by the system is defined by potential etch points, in which the breakdowns required to create the image in the selected optically transparent material are possible. The potential etch points are generated based on the characteristics of the selected optically transparent material. If the number of the potential etch points exceeds a predetermined number, the system carries out an optimization routine that allows the number of the generated etch points to be reduced based on their size. To prevent the distortion of the reproduced image due to the refraction of the optically transparent material, the coordinates of the generated etch points are adjusted to correct their positions along a selected laser beam direction.
U.S. Pat. No. 6,333,485 to Haight, et al. discloses a method for minimizing sample damage during the ablation of material using a focused ultra short pulse beam. The beam is focused above the surface of a material where laser induced breakdown is desired. The region of least confusion (minimum beam waist or average spot size) is above the surface of the material in which laser induced breakdown is desired since the intensity of the beam falls in the forward direction.
U.S. Pat. No. 6,333,486 to Troitski discloses method and laser system for creation of laser-induced damages to produce high quality images. Accordance to the invention, a laser-induced damage is produced by simultaneously generating breakdowns in several separate focused small points inside the transparent material area corresponding to this etch point. Damage brightness is controlled by variation of a number of separate focused small points inside the transparent material area.
U.S. patent application Ser. No. 09/583,454 to Troitski (the application is allowed for issuance as a patent) discloses method and laser system controlling breakdown process development and space structure of laser radiation for production of high quality laser-induced damage images. Accordance to the invention, at the beginning an applied laser radiation level just exceeds an energy threshold for creating a plasma condition in the material, and thereafter the energy level of the applied laser radiation is just maintain the plasma condition. Accordance to another method a laser generates a TEMmn radiation. The values of the integers m and n are controlled and determined so as to reproduce particular gray shades for a particular point of an image.
U.S. Pat. No. 6,399,914 to Troitski discloses methods and an apparatus for creating high quality laser-induced damage images. One or more embodiments of the invention comprise a method for producing laser-induced damage images inside the special transparent material containing special kinds of impurities, which decrease the damage threshold of the material. Colored laser-induced damage images are produced inside transparent materials containing color impurities. Laser radiation is focused inside the transparent material in such a way that focal area contains at least one said impurity. Other embodiments of the invention comprise a method and a system for producing laser-induced images by using two lasers. The first laser generates radiation, which heats the predetermined material area about a point, where breakdown should be produced, to the vitrify temperature. The second laser generates radiation, which creates breakdown in a point of the heated area after the area is heated to the vitrify temperature.
U.S. Pat. No. 6,322,958 to Hayashi discloses a marking method using a laser beam and laser marking apparatus for forming a marker in a transparent member. The laser beam is converged at the points of the material to form cracks, which have shape long in a direction perpendicular to an optical axis of the laser beam.
U.S. Pat. No. 6,322,958 to Hayashi discloses a method for making marks in a transparent material by using a laser. A mark is formed in the region of the object to be marked where the laser beam is focused. Generation of dirt caused by marking, rupturing of the object to be marked, and the like, can be prevented.
U.S. patent application Ser. No. 09/651,076 to Troitski (the application is allowed for issuance as a patent) discloses the method and laser system for production of high quality single-layer laser-induced damage portraits inside transparent material.
U.S. patent application Ser. No. 10/117,592 to Troitski et al. discloses the method for producing images containing laser-induced color centers and laser-induced damages. These color centers are produced in a result of photoionization generated by laser radiation with energy lower the breakdown threshold.
The publication xe2x80x9cNew results on avalanche ionization as a laser damage mechanism in transparent solidsxe2x80x9d to A. Manenkov describes theoretical and experimental investigations of the interaction of laser radiation with transparent material.
The publication xe2x80x9cEffects of high-power laser radiationxe2x80x9d to John Ready describes effects accompanying creation laser-induced damages.
The publication xe2x80x9cTemperature dependent effects in laser induced damagexe2x80x9d to M. Lange at al. describes the temperature dependence of various process can be extremely important in laser induced damage mechanisms.
The experiments described in a publication entitled xe2x80x9cPhotoionization of silicate glasses exposed to IR femtosecond pulsesxe2x80x9d (O. M. Efimov et al., Journal of Non-Crystalline Solids 253 (1999), 58-67) show that photoionization of silicate glasses is possible under infrared (IR) high-power femtosecond (about 100 fs) pulses, and color centers are generated by laser pulses at irradiance below the thresholds of laser-induced damage and catastrophic self-focusing.
The publication xe2x80x9cSystem for creation of laser-induced damage images and problems of their optimizationxe2x80x9d (I. N. Troitski, Proc. of SPIE Vol. 3902 (2000), 489-499) describes methods for generating 3D images and portraits allowing reproduction of them within an optically transparent material with the same resolution like computer images, without sharp point structure and without significant fluctuation of gray shades.
The publication xe2x80x9cExperience of creation of laser-induced damage imagesxe2x80x9d (I. N. Troitski, Proc. of SPIE Vol. 3902 (2000), 479-488) discloses the specific system for production of laser-induced damage images.
The publication xe2x80x9cImage recording by laser-induced damagesxe2x80x9d (I. N. Troitski, Optical Memory and Neural Networks, Vol. 9, No. 4, (2000) 233-238) discusses the problems of laser-induced damage utilization for image recording.
The publication xe2x80x9cLaser-induced color centers in silicaxe2x80x9d (Linards Skuja,et al., SPIE Volume 4347 (2000) 155-167) reviews the color centers contributing to the optical absorption spectrum of synthetic silica glass in the near infraredxe2x80x94to vacuum UV range. The optical properties of common impurities/dopants in synthetic silicas used in laser optics are discussed.
The publication xe2x80x9cMethod and laser system for creating high-resolution laser-induced damage imagesxe2x80x9d (I. N. Troitski, Proc. of SPIE Vol. 4679 (2002), 392-399) describes creation of small laser-induced damages without large star structure by the specific temporal radiation.
The present invention has its principal task to provide a method for the production of laser-induced color images within three-dimensional transparent media, and more particularly, inside the photosensitive glass.
One or more embodiments of the invention comprise a method for creation of a latent image inside the photosensitive glass by focusing IK ultra short (from femtosecond to picosecond) laser pulsed radiation into separate areas of the created image, so that focal spot sizes are approximately equal to the sizes of the resolution element of the created image. During the latent image creation, the laser power is lower the breakdown threshold, but has enough value to create the radiation with broad spectrum.
One or more embodiments of the invention comprise a method for development of the latent image to the visible image by focusing of the laser pulses at the points of the latent image, so that focal spots are essentially smaller than the resolution element. During the visible image development, the laser power increases the breakdown threshold, and the breakdown is generated so way that the laser-induced damage is practically invisible.
One or more embodiments of the invention comprise a method, in which the control of color and its intensity is produced during creation both the latent and visible images by changing the laser power value and the number of the laser pulses focused at the predetermined area.
One or more embodiments of the invention comprise a method wherein the breakdown plasma generates the ultraviolet light, which creates the latent image; the breakdown plasma is created by series of laser pulses focused at many points of the image area, so that the first pulse generates the plasma, which is maintained by the following pulses.
One or more embodiments of the invention comprise a method wherein a color image inside the photosensitive glass is produced by creating the latent image, focusing pulsed laser radiation for generating of the ultraviolet radiation, and by developing the visible color image, using ordinary heat treatment of whole photosensitive glass.
One or more embodiments of the invention comprise a method wherein a color image inside the photosensitive glass is produced by the irradiation of the photosensitive glass using standard ultraviolet radiation and by development of the visual image using controlling heat treatment basing on the focusing laser pulsed radiation and generation of laser-induced breakdowns at the focusing points.